Manual transmissions of countershaft design and that can be actuated with manual shifting devices have long been in use in drive-trains of motor vehicles. In a conventional countershaft transmission loose wheels and fixed wheels, which mesh in pairs, are usually arranged in a number of gearset planes. In each case, the shifting of transmission gears is accomplished by opening a gear clutch of a gear that is engaged and closing a gear clutch of a target gear, whereby a rotationally fixed connection between a loose wheel and a gear shaft on which the loose wheel concerned is mounted to rotate is released, whereas another rotationally fixed connection between a loose wheel and a transmission shaft is formed. Before the formation of the force closure in the drive-train, the rotating components of the target gear that have to be engaged are synchronized. In order to save space and weight the gear clutches, i.e. the synchronizing devices or claw clutches of the shifting devices, are where possible formed as dual clutches such that two gear clutches or synchronizing devices at a time are arranged in shifting packets that can be actuated from both sides. The number of gears in such transmissions usually corresponds to the number of gearset planes.
To obtain more gears with a given number of gearset planes or, for a set number of gears, to produce a more compact and cost-saving structure with fewer gearset planes, it is already known to set up shifting logic systems in which, to produce the transmission gears, existing gearset planes and gear clutches are used more than one at a time. In such manual transmissions, due to the smaller number of components, to produce a force flow in the transmission when the gears are engaged in each case more than one gear clutch is closed or is kept closed.
The design of a manual shifting device for such a transmission is relatively complex, as shown for example by DE 10 2008 017 862 A1 from which an operating device for a 7-gear manual transmission with an H-type shifting pattern is known.
Thus, such transmissions are usually actuated by means of actuators which are controlled automatically by a control unit by virtue of a shifting program. But if such a compact manual transmission is to be operated by a driver as a manually shifted transmission with shift-lever actuation in a logical shift pattern, then in order to limit the design complexity it is appropriate to actuate at least part of the gearshift, i.e. in each case at least one of the gear clutches to be engaged for the gearshift, automatically with the help of an actuator.
When the shift lever is guided in the gearshift consoles of such a manual-shift device of an at least partially automated transmission, shift processes are initiated by actuator means and/or control elements of the transmission are operated manually. For this, gear clutches can be actuated both by shifting movements in the shifting gates of the gearshift console and also by selector movements in the selection gates of the gearshift console. This entails a correspondingly high level of complexity for the actuators and their control.
DE 10 2005 057 813 A1 describes a manual shift transmission with an input shaft, an output shaft arranged coaxially with and behind it, and a countershaft arranged with its axis parallel to these shafts. The transmission gears can be engaged in each case by closing more than one gear clutch. The transmission comprises five gearset planes for the production of six forward gears and one reverse gear, such that the fifth gear is designed as a direct gear and the sixth gear as an overdrive gear, i.e. a fast-driving gear. The third and fourth gearset planes consist in each case of two meshing loose wheels, the loose wheels on the countershaft side of the two gearset planes being firmly connected with one another. On the input shaft, the output shaft and the countershaft are arranged a total of seven gear clutches, arranged as three dual gear clutches and one single clutch. By suitable adaptation of the radial dimensions of the gear clutches, all the gear clutches can be mechanically actuated by way of a single shifting shaft or shifting roller.
DE 10 2010 043 564 A1 describes a manual shift transmission with a manual shifting device, which is designed as a group transmission. This transmission comprises an input shaft, an output shaft arranged coaxially with and behind it, and a countershaft arranged parallel to the shafts. With five gearset planes, six forward and one reverse gear can be obtained. The first two gearset planes act as a splitter group, wherein the second gearset plane is also active with the other gearset planes in a main group. Of the total of six gear clutches three are formed as dual clutches, and one of the dual clutches is connected to the input shaft while the other two dual clutches are connected to the output shaft. All the loose wheels are arranged on the input shaft and the output shaft, whereas all the fixed wheels are connected to the countershaft. The transmission can be shifted in an H-shifting pattern having a plurality of shifting gates and a selection gate orientated transversely thereto, such that when any gear is engaged, two of the gear clutches are in each case closed and in the shifting gates with two opposite gears in each case one of the gear clutches in the two gears is closed. Several of the gear clutches can be actuated both in the selection gates and also in one or more of the shifting gates. A comparable transmission is also known from DE 197 53 061 C1.